1. Field of the Invention
The present invention relates to foods, including food materials and processed food products, which contain a novel enzyme-treated protein, methods for producing the foods, and an enzyme preparation for producing the foods. In the present invention, the enzymes transglutaminase and oxidoreductase are used for protein modification. Optionally, a substrate of an oxidoreductase, a protein partial hydrolysate, milk protein and/or a thiol group-containing material, may be used in the modification, if desired.
The two enzymes may be used during the general production processes of a variety of foods, and the enzymes can also be used in the form of enzyme preparation for the modification of the protein in foods including food materials and processed food products. The enzyme preparation may be used to modify a wide variety of food materials and processed food products containing protein. Such substrates include, for example, wheat flour, fish paste, poultry and cattle meats, soybean protein and egg white, and in processed foods including wheat-processed foods such as bread, noodles and confectionery, fish-processed foods such as fish cake, fried fish cake and baked fish paste in cylindrical shapes (chikuwa), and cattle meat-processed foods such as ham. The enzyme preparation exerts excellent effects on the modification of food materials such as soft wheat, fresh-water fish paste, poultry and cattle meats, soybean protein, and egg white.
2. Discussion of the Background
Many attempts have been made to modify protein-containing food materials. A large amount of research effort has been carried out regarding the modification of the protein in wheat flour for use in breads, noodles, confectionery and cakes.
For example, processes have been proposed, including a process of putting wheat flour in contact to carbonate gas and ethanol at 40xc2x0 C. or higher (see JP-B-6-36725); a process of recovering gluten with excellent processability for production of processed foods, comprising adding an oxidant and water to wheat flour (see JP-B-6-34682); and a process of modifying wheat to prepare a type of wheat flour suitable for confectionery, comprising adding water at 40 to 500% by weight to wheat and drying then the resulting mixture at a temperature with no occurrence of the modification of the wheat (see JP-B-5-4055).
A process for modifying wheat flour is also proposed by using transglutaminase (abbreviated as TG hereinafter) catalyzing the transfer reaction of the acyl group in the xcex3-carboxyamide group of a glutamine residue in a peptide. For example, a process for generating wheat flour with excellent texture for cake is proposed, comprising adding a given amount of TG to wheat flour for cake (see JP-A-2-286031), which is for example a process for preparing bread dough with springiness (U.S. Pat. No. 5,279,839). Furthermore, a process for preparing modified wheat flour is proposed, comprising spraying an aqueous enzyme solution to wheat flour after milling, and subsequently heating, drying and grinding the resulting flour (see JP-A-10-56948).
The known processes are excellent in some aspects, but these processes are still unsatisfactory as means for improving the physico-chemical properties of wheat flour, in view of the production aspects, safety profile, and economy. Accordingly, these processes do not overcome the conventional problems in terms of economy, simplicity and functionality.
Among various types of wheat flour, domestic wheat flour has drawbacks in that the physico-chemical properties thereof are poor because of the presence of soft albumen therein, and in that the flour is apparently of a poor color tone due to the ash content therein. These drawbacks have conventionally been barriers for the enlargement of the application of domestic wheat flour. These problems have not yet been completely overcome.
Meanwhile, it has been reported that fish-paste products having the quality of shape retentivity and moldability and with springiness can be prepared from a low-quality fish paste, by using a combination of TG and an alkali earth metal salt (see JP-A-6-113796). Although the shape retentivity and springiness of low-quality fish paste can thereby be improved therein, even the combination cannot give flexible and smooth texture with good bite to the resulting fish-paste products, although these properties are demanded for fish paste products. It has been very difficult to modify low-grade fish pastes with poorer gelation potency and deteriorated colors and flavor, like fish pastes prepared after landing, compared with fish pastes prepared at sea.
Besides the research works so as to overcome the problems regarding sea-water fish, research works have been promoted in China and East Asia to enlarge the applicable range of fresh-water fish of a possible importance as a fishery resource in the near future as food. Compared with fish pastes prepared from sea fish, those prepared from fresh-water fish have low gelation potency; the gelation potency thereof is rapidly lowered (deteriorated) at a temperature zone around 60xc2x0 C., particularly significantly. In preparing fish paste products from fresh-water fish pastes, therefore, the gelation potency is lowered because these pastes are exposed to temperatures around 60xc2x0 C. during treatment processes or under heating. Hence, the resulting fish paste products do not have the desired sensory properties when eaten.
For the production of cattle-meat-processed foods, such as ham, bacon and roasted pork, pickles are generally used for the modification of poultry and cattle meats by the following processes; an immersion process of immersing such meats in pickles; an injection process of injecting a pickle into meats; and a process of injecting a pickle into a meat and additionally adding another pickle as a covering pickle to the resulting meat with a tumbler. As well known in the art, pickles are essential for the production of cattle-meat-processed products including ham and bacon. As used herein, the term xe2x80x9cpicklesxe2x80x9d refers to aqueous solutions of salt and brine-mix preparations of color fixatives such as nitrite salts. Current pickles contain sugar, color fixatives such as nicotinamide, absorbate salts, meat quality modifiers such as polyphosphate salts, and seasonings such as glutamic acid. For the purpose of the improvement of water-holding capacity, emulsifiability, texture profiles such as hardness and elasticity as well as binding property, additionally, pickles are now predominant, comprising a blend with extraneous protein materials including egg white, whey protein, sodium casemate and soybean protein.
When these extraneous protein materials are added to a pickle in too large of an amount, the flavor thereof adds peculiar odor with a different taste to the resulting products, causing severe deterioration of the quality thereof and the viscosity increase of the pickle, so that the pickle can hardly be injected by means of any injector. When these extraneous protein materials are added to a pickle at a too low concentration, the potential effects of the pickle become weak. It cannot be denied that a pickle blended with proteinous materials conventionally used can exert the intended effects only in a limited manner.
So as to overcome the problem, a method has been proposed, comprising injecting a pickle into ham and the like, wherein a ratio of sodium casemate and soybean protein causing the increase of the viscosity of a solution of the pickle is reduced by using TG (see JP-A-7-255426). However, the composition of the pickle definitely defines the quality of the final food products. Thus, each company in the food industry has its own unique blend technique. As such, the modification of the blend ratio or absolute content of an extraneous protein even for the suppression of viscosity increase is so deleterious that the method is very rarely adopted in a practice.
Soybean protein, a very nutritious, economical food material under ready supply, is now drawing considerable attention. Processed food products from fish and cattle meats through the addition thereto of soybean protein have the problem of smooth touch during swallowing and are poor in terms of color and flavor. Various countermeasures have been adopted against these problems, but no satisfactory solution has been found yet.
Egg white is a protein material for use in a diversified range of food processing, having functions for gelation, emulsification and forming ability. Egg white is an excellent proteinous material, but a gel prepared by heating this material, for example, has high springiness, but low visco-elasticity. Additionally, glucose at a content of about 1% in egg white causes color change therein due to the emergence of browning and the gel further lacks smoothness. Accordingly, a process of removing the sugar from egg white at the production process of egg white powder is drawing attention. To solve these problems unique to egg white, attempts have been made to improve the gelation property of egg white by a general means comprising adding protein modifiers including reductive agents and salts, to egg white. Nevertheless, food additives per se are now likely to be shunned and the effects thereof are low. However, various food industrial companies have made attempts to improve the process of removing the sugar in a variety of fashions, but even the improvement brings about only insufficient effects. As has been described above, how to give high visco-elasticity to the heated gel of egg white and how to improve the color are topic issues for the production of egg white powder.
Conventional methods for food binding include for example a method by means of TG and casein (JP-A-6-284867 and JP-A-8-140594) or a method by means of wheat protein. The former is problematic in that bound areas are discriminated on the resulting bound fresh meat blocks, sometimes causing improper appearance. The latter is problematic in that the range of food types which can be bound with the wheat protein is so narrow from the standpoints of taste and flavor that the wheat protein is applicable only to a limited range of utilities. So as to get an enhanced binding strength to prepare preferable appearance with good taste and flavor, furthermore, a binding technique is now demanded.
As has been described above, none of the conventional protein modification methods is satisfactory as a modification method to prepare a modified protein with good gelation potency (satisfactory properties in terms of all of shape retentivity, cohesiveness, water-holding capacity and binding property), as well as with excellent color and flavor.
It is an object of the invention to provide foods with improved sensory properties.
It is another object of the invention to provides foods which have improved texture, flavor and/or color.
It is also an object of the present invention to provide a method for modifying the protein of a protein-containing food in a simple, economical manner.
The present invention is based, in part on the discovery that protein-containing food materials and various protein-processed food products can be produced to avoid the disadvantages discussed above, by incorporating into the food materials a protein treated with TG and oxidoreductase.
Accordingly, the objects of the present invention, and others, may be accomplished with a food containing a protein treated with at least one transglutaminase and at least one oxidoreductase.
The objects of the invention may also be accomplished with a method for preparing the food by treating a food material containing a protein with at least one transglutaminase and at least one oxidoreductase.
The objects of the invention may also be accomplished with an enzyme preparation comprising at least one transglutaminase and at least one oxidoreductase.
The objects of the invention may also be accomplished with a pickle suitable for processing poultry and cattle meats, comprising at least one transglutaminase and at least one oxidoreductase.
The objects of the invention may also be accomplished with a method for preparing the food by incorporating into a food material a protein treated with at least one transglutaminase and at least one oxidoreductase.
The objects of the invention may also be accomplished with a method of preparing a food containing a protein treated with at least one transglutaminase and at least one oxidoreductase, by contacting a food containing the protein with the enzyme preparation described above.
The objects of the invention may also be accomplished with a method of preparing a food containing a protein treated with at least one transglutaminase and at least one oxidoreductase, comprising contacting a food containing the protein with the pickle described above.
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description.
A feature of the present invention is the modification of food materials, such as wheat flour, fish pastes, poultry and cattle meats, soybean protein and egg white, to dramatically improve various diverse properties of the food materials. Such properties include, for example, smooth touch during swallowing and excellent bite, i.e., texture, as well as color and flavor. These improvements are based on the presence of the protein treated with the TG and oxidoreductase in the food material.
Thus, the invention relates to a food containing a protein treated with at least one transglutaminase and at least one oxidoreductase. The treatment with the two enzymes may be conducted simultaneously or separately. For example, either of the two enzymes is used first for the treatment, followed by the treatment with the other enzyme; otherwise, the two enzymes are alternatively used in repetition for the treatment. Another treatment may be added if necessary, and this is also encompassed within the scope of the invention.
The following embodiments are also encompassed within the scope of the present invention:
1. A food as described above where the protein is further treated in the presence of at least one of the following: a substrate of the oxidoreductase, a protein partial hydrolysate, milk protein and a thiol group-containing material.
2. The food may be a food material or a processed food product.
3. The food where the oxidoreductase comprises at least one member selected from the group consisting of glucose oxidase, absorbate oxidase and catalase.
4. The food where the protein includes at least one member selected from the group consisting of wheat protein, proteins of fish species such as fresh-water fish species, poultry and cattle meats, soybean protein and egg white protein.
5. An enzyme preparation containing transglutaminase (TG) and oxidoreductase or containing a combination thereof.
The enzyme preparation may contain these two enzymes as a mixture; the enzyme preparation may comprise an enzyme preparation containing TG and an enzyme preparation containing oxidoreductase, or may comprise a combination of these enzyme preparations when these enzymes are intended for use in the modification of the same protein. Thus, the enzymes may be separately packaged in the preparation.
The enzyme preparation may be used for modifying the properties of a protein contained in a food material or a processed food product or a protein to be used for a food material or a processed food product. The enzyme preparation may be used as a protein-modifying agent. The enzyme preparation for direct use for protein modification and the enzyme preparation intended for indirect use therefor are both within the scope of the present invention. The enzyme preparation may also be used in a pickle for processing poultry and cattle meats, in particular.
6. A pickle for processing poultry and cattle meats, where the pickle contains at least one of TG and oxidoreductase.
On a solid basis, the pickle may contain TG in preferably about 1 to 1,000 units, more preferably about 5 to 500 units per 100 g of solid in the pickle and contains oxidoreductase preferably about 1 to 1,000 units, more preferably about 5 to 500 units per 100 g of solid in the pickle. The pickle may satisfactorily contain additionally at least one of a substrate of the oxidoreductase, a protein partial hydrolysate, milk protein and a thiol group-containing material, at their amounts each of preferably about 0.01 to 50 g, more preferably about 0.05 to 30 g per 100 g of solid in the pickle.
7. The enzyme solution or the pickle additionally containing at least one of the following: a substrate of the oxidoreductase, a protein partial hydrolysate, milk protein and a thiol group-containing material, as described in (5) or (6) above.
Per one gram of enzyme preparation described in (5) above, at least one of the following: a substrate of the oxidoreductase, a protein partial hydrolysate protein products, milk protein and a thiol group-containing material is used at their amounts each of preferably about 0.001 to 0.9 g, more preferably 0.01 to 0.3 g; if necessary, other additives may satisfactorily be used alike. As described above, these components are in a blend formulation in the same preparation or are in a combination of formulations for the purpose of the modification of the same protein. In a pickle, the components are used at their amounts as described above.
8. The enzyme preparation described in (5) above, where the enzyme preparation contains TG of about 0.01 to 1,000 units, preferably about 0.1 to 500 units and oxidoreductase of about 0.01 to 1,000 units, preferably about 0.1 to 500 units, per gram of the enzyme preparation.
9. A method for preparing a protein-containing food, comprising a treatment step with TG and oxidoreductase.
The two enzymes, i.e., TG and oxidoreductase, may be used at the following units per g of protein to be treated; TG at about 0.01 to 200 units, preferably about 0.1 to 100 units, and oxidoreductase at about 0.01 to 200 units, preferably about 0.1 to 100 units. At least one of a substrate of the oxidoreductase, a protein partial hydrolysate, milk protein and a thiol group-containing material is used at about 0.0001 to 0.9 g, preferably about 0.001 to 0.3 g, when the two enzymes are used at the amounts described above.
10. The method described in (9) above, where the treatment step with TG and oxidoreductase is conducted by contacting or adding the enzyme preparation in (5) or the pickle in (6) above to a protein-containing food.
For use, the enzyme preparation may be added to exert the activities in the form of an enzyme mixture of the two or in the enzyme mixture with further addition of other compounds (e.g., a substrate of the oxidoreductase, a protein partial hydrolysate, milk protein and a thiol group-containing material) intended for concurrent use, other than the two enzymes. Additionally, the two enzyme components may be separately added one by one or the two enzyme components and other components for the- treatment are separately or simultaneously added to exert their activities. These methods are also encompassed within the scope of the invention.
11. The method described in (9) above, where the treatment process with transglutaminase and oxidoreductase is included in any of the tempering process of milling, a process of preparing fish paste (for example, paste of fresh-water fish), a process of preparing soybean protein, a process of preparing egg white and a treatment process of poultry and cattle meats (immersion and injection process).
Finally, modified wheat flour and processed food products thereof, modified fish paste and processed food products thereof, modified soybean protein and processed food products thereof, modified egg white and processed food products thereof and modified poultry and cattle meats and processed food products thereof can be produced.
12. An enzyme preparation containing TG or oxidoreductase and for executing a modification treatment of a protein, when used concurrently with oxidoreductase or TG.
Because the oxidoreductase serves as a chemical agent to promote the effects of TG on the functional modification, in particular, the oxidoreductase-containing enzyme preparation can be designated as an auxiliary agent of TG for protein modification. The TG-containing enzyme preparation can also effectively work for protein modification, when used concurrently with the oxidoreductase.
The invention is characteristic in that the treatment with two enzymes can treat and modify protein; for practicing the invention, the enzyme preparation of the present invention is effectively used in a simple manner. The enzyme preparation is one preferable, typical example of the invention and is mainly described below. But the invention is not limited thereto.
The enzyme preparation of the present invention is a formulation containing TG and oxidoreductase and serves for protein modification; the enzyme preparation preferably contains at least one of a substrate of the oxidoreductase, a protein partial hydrolysate, milk protein and a thiol group-containing material, and may additionally contain food excipients, if necessary, and various other additives, if necessary.
These enzymes and components are mixed together and contained in one preparation, but these are in a formulation of a combination thereof or in formulations of separate combinations thereof. Furthermore, preparations containing separately two enzymes or a preparation containing a combination of the two enzymes is included as a modification-promoting agent or a modification-supplementing agent within the scope of the invention, when the preparations or the preparation is for the same purpose of protein modification.
The enzyme preparation of the present invention contains TG of about 0.01 to 1,000 units per g of enzyme preparation. Below 0.01 unit in the enzyme preparation, the crosslinking ability of TG is too low enough to modify protein. Above 1,000 units, alternatively, the crosslinking reaction progresses excessively so that the texture of the resulting processed food products gets fragile, with the resultant poor texture during swallowing.
In accordance with the invention, use is made of TG as an enzyme catalyzing the transfer reaction of the acyl group in the y-carboxyamide group in the glutamine residue in the peptide chain of protein. When TG reacts with c-amino group in the lysine residue in a protein as an acyl receptor, xcex5(xcex3-Glu)-Lys bonds are formed within the molecule of the protein or between the molecules. The crosslinking bonds promote crosslinking polymerization of the protein in wheat flour or fish paste, so that a material with characteristic properties including gelation potency, high viscosity and great waterholding capacity, can be recovered.
Any TG can be used in accordance with the invention, as long as the TG has a transglutaminase activity; as the TG, therefore, known TGs may be used (see JP-B-1-50382, incorporated herein by reference). TG from a microbial origin is preferable because the TG does not require Ca for the exertion of the activity thereof. For example, a known TG derived from a microorganism has these properties (see JP-A-64-27471, incorporated herein by reference).
TG is divided into calcium-independent and calcium-dependent types. Either can be used in the present invention. Examples of the former include those derived from microorganisms such as Actinomycetes, Bacillus subtilis and the like (see, for example, JP-A-64-27471). Examples of the latter include TG derived from guinea pig liver (see, for example, JP-B-1-50382, incorporated herein by reference), TG derived from microorganisms such as Oomycetes, those derived from animals such as bovine blood, swine blood and the like, TG derived from fishes such as salmon, red sea bream and the like (see, for example, Seki Nobuo et al., Nippon Suisan Gakkaishi, vol.56, No.1, pp.125132 (1990), each incorporated herein by reference), TG derived from oyster, and so forth. Also, TG produced by methods of genetic engineering (see, for example, JP-A-1-300889, JP-A-6-225775, JP-A-7-23737, each incorporated herein by reference) may be used. In accordance with the present invention, any of these transglutaminases can be used, with no specific limitation on the origin and the preparation. However, in view of the function and the economics in the food applications, the calcium-independent transglutaminases are preferable. For example, the transglutaminases derived from microorganisms (JP-A-64-27471, mentioned above) and are preferred enzymes.
The activity unit of TG for use in accordance with the invention is assayed and defined as follows. More specifically, TG is allowed to react with substrates benzyloxycarbonyl-L-glutaminylglycine and hydroxylamine to generate hydroxamic acid, which is then converted to an iron complex in the presence of trichloroacetic acid, to assay the quantity of the iron complex as the absorbence at 525 nm. Using the quantity of hydroxamic acid assayed in such manner, a standard curve is prepared; the quantity of the enzyme generating 1 xcexcmol hydroxamate per minute is defined as one unit of the TG activity unit. The assay is described in detail in JP-A-64-27471, incorporated herein by reference.
Various enzymes may be candidates for the use in combination with TG, but oxidoreductase is effective for overcoming the problems discussed above.
As the oxidoreductase, for example, glucose oxidase, absorbate oxidase, catalase, polyphenol oxidase, peroxidase, dehydrogenase and reductase may be used. From the aspect of supply, economy, safety profile and functionality for foods, in particular, glucose oxidase, absorbate oxidase or catalase are used preferably or reductase in the present invention.
The oxidoreductase is contained at about 0.01 to 1,000 units per gram of the enzyme preparation of the present invention. Below 0.01 unit per gram of the enzyme preparation, the activity of the enzyme is too low so that the effect cannot be exerted. Above 1,000 units, alternatively, the modification effect is not any more enhanced, disadvantageously uneconomically, even if the amount of the enzyme preparation is increasingly added. Enzymes for general use in food processing such as amylase, xylase, hemicellulase, pentosanase, lipoxydase and lipase, other than the oxidoreductase, may serve as the structural components of the enzyme preparation of the present invention; proteases may satisfactorily be used in combination, within a range with no suppression of TG or the oxidoreductase contained in the enzyme preparation of the present invention.
The activity assay of the oxidoreductase varies depending on the enzyme species, but generally, glucose oxidase can be assayed by determining gluconic acid generated through the enzyme reaction; and absorbate oxidase can be assayed by determining dehydroascorbic acid generated through the enzyme reaction. One unit of glucose oxidase is defined as the enzyme quantity oxidizing 1 xcexcmol glucose per one minute at 40xc2x0 C. and pH 7.0 to generate gluconic acid.
It is preferable to concurrently use at least one of a substrate of the oxidoreductase, a protein partial hydrolysate, milk protein and a thiol group-containing material, from the aspect of improving the functions of TG.
Examples of the substrate of oxidoreductase include xcex2-D-glucose or FAD when glucose oxidase is used, ascorbic acid and its salts when absorbate oxidase is used, and hydrogen peroxide when catalase is used, and so on. Each oxidoreductase catalyses its own specific reaction, and its own substrate takes part in the reaction. A substrate suitable for the oxidoreductase used in the invention is selected. The substrate is used at an amount of about 0.0001 to 0.9 g, preferably 0.001 to 0.3 g, as the total with the following protein partial hydrolysate, milk protein and a thiol group-containing material. When none of the protein partial hydrolysate, milk protein and thiol group-containing material is used, the substrate is singly used at the amount described above.
Examples of the protein partial hydrolysate include a wheat flour protein partial hydrolysate, a milk protein partial hydrolysate, a soybean protein partial hydrolysate and a gelatin partial hydrolysate. These are produced by hydrolysis of the individual proteins by enzymes or acids or alkalis, with no specific limitation, as long as the enzymes or acids or alkalis can meet the objects of the invention. Because commercially available peptides such as lysine peptide have effects similar to those of the protein partial hydrolysate described above, peptides composed of any single amino acid, such as lysine peptide, are also included in the protein partial hydrolysate in accordance with the invention. The protein partial hydrolysate for use in accordance with the invention may have a mean molecular weight of about 600 to 80,000, preferably 1,000 to 20,000.
The protein partial hydrolysate is used at an amount of about 0.0001 to 0.9 g, preferably 0.001 to 0.3 g per g of enzyme preparation, as the total with a substrate of the oxidoreductase, milk protein and a thiol group-containing material.
Casein salts, such as sodium casemate and calcium casemate are used as the milk protein, preferably from the respect of the solubility, but caseins containing acid casein and milk whey protein may also be used.
The milk protein is used at an amount of about 0.001 to 0.9 g, preferably 0.01 to 0.3 g as the total with the protein partial hydrolysate and a thiol group-containing material.
Examples of the thiol group-containing material include glutathione and cysteine; yeast extract containing a high concentration of glutathione is practically preferable in view of economy, functionality, rules over food additives, shelf life, and taste and flavor, compared with the remaining substances. Furthermore, the thiol group-containing material additionally have functions to allow TG to exert its activity and stably retain the activity.
The thiol group-containing material is used at an amount of about 0.001 to 0.9 g, preferably 0.01 to 0.3 g, per gram of the enzyme preparation, as the total with the aforementioned three components such as a substrate of oxidoreductase.
As has been described above, food excipients can be used in the enzyme preparation of the present invention. As the excipients, general food excipients are used, including for example saccharides, starches, protein, and thickening polysaccharides. Examples of the saccharides include monosaccharides such as glucose, disaccharides such as lactose and sucrose, oligosaccharides, dextrins, and sugar alcohols such as sorbitol. The starches include various carbohydrates and hydrolyzed starch; and the protein includes soybean protein, milk protein, skim milk, wheat protein, egg white, and plasma protein. Herein, care should be taken when such protein is used, because protein serves as a substrate for TG.
The method of the producing the food according to the present invention is described below.
The inventive method provides a modified protein via treatment of a protein with TG and oxidoreductase, or for producing diverse protein-containing food products such as processed foods, if necessary. These enzymes can be used simultaneously or separately. Within the scope of the objects of the present invention, another treatment may be effected, including the treatment with at least one of a protein partial hydrolysate, milk protein and a thiol group-containing material and other treatments. TG is used according to conventional methods for treatment with TG.
For the enzyme treatment, the enzyme preparation of the present invention is advantageously used in a simple manner. Then, the method for modifying a food material rob such as wheat flour fish paste, poultry and cattle meats, and soybean protein, by using the enzyme preparation of the present invention, will now be described. The treatment method by using the enzyme preparation is just one example of the method for treatment with TG and oxidoreductase, in accordance with the invention. Accordingly, the invention is not limited thereto.
As an example, the use of wheat is described. As well known, wheat is milled by a method comprising grinding wheat grain and separating the shell fraction from the resulting pulverized wheat grain powder, because wheat grain has hard outer shell with fragile and readily break albumen and with a longitudinal groove at the core part of the grain.
The milling process is summarized and described as follows (see for example General Food Industry Dictionary, New Edition, issued by Korin, Co., 1993).
1. Fractionation
A process of removing contaminants such as small stone pieces and the like. Because the removal of impurities is very hard from the final product wheat flour, the raw material wheat is preferably fractionated very carefully.
2. Tempering and Blending
For the purpose of allowing the albumen readily separable by making the shell more hard and for the purpose of allowing the albumen to be softened and be thereby ground readily, water is added to wheat grain, which is then aged for one to two days through nights for tempering. If necessary, additionally, wheat grain types separately tempered as raw materials are blended together at a ratio, depending on the purpose.
3. Milling
From the tempered wheat is separated the shell as much as possible by means of break roll, to recover the albumen in coarse grains (disruption process). Then, the coarse grains are fractionated in size and fed into a purifier, where the contaminated debris of the shell is removed by means of sieving and air fractionation (purification process). Furthermore, the purified coarse grains are ground by means of smooth roll (on smooth face or coarse face), which are then sieved on the basis of powder grain size (grinding process).
4. Recovery of Wheat Flour
Sieved wheat flour fractions of various particle sizes (finished flours) are blended together at a ratio, in conformity with the quality and grade of an objective wheat flour type.
5. Final Process
Thorough mixing for preparing a final product. For supplement, vitamins and the like are mixed with the flour at this process.
For use, the enzyme preparation of the present invention is mixed with milled wheat flour after addition of water thereto, or the enzyme preparation is added to wheat grain at the milling process. The enzyme preparation of the present invention can exert the effects more efficiently, when the enzyme preparation is added at the milling process. In that case, the treatment with at least one of TG, oxidoreductase, a protein partial hydrolysate, milk protein and a thiol group-containing material is particularly preferably executed at a tempering process as described below.
At a tempering process after the fractionation of the raw material wheat grain, TG and oxidoreductase are added, within the range of the amounts thereof to be added, to water, along with if necessary, a protein partial hydrolysate (for example, a wheat protein partial hydrolysate, and a milk protein partial hydrolysate) and/or milk protein and/or a thiol group-containing material, at the timing of water addition during tempering. The amount of water then is with not any specific limitation; water should be added to a final water content in wheat flour to about 14 to 16%, starting from the general water content of ca. 9 to 14% in wheat flour. Subsequently, tempering is effected in a tank for 16 to 50 hours, for passing TG and the oxidoreductase and the like from the surface of wheat grain through wheat germ to allow these enzymes and the like to infiltrate into the inside thereof. The albumen is readily ground through tempering, while the surface shell absorbs appropriate moisture and is hardened owing to the TG action, so that the shell turns fragile and readily breaks. Additionally, the gluten inside the albumen is crosslinked and polymerized together through the TG action, so that springiness is imparted to the resulting wheat flour.
After the tempering process, these processes may be conducted as follows.
Tempered wheat grain is subjected to a water addition process, one to 3 hours prior to the grinding process. As in the processing method at the tempering process, the processing method then comprises uniformly spray coating water dissolving therein at least one of TG, a substrate of the oxidoreductase, a protein partial hydrolysate, milk protein and a thiol group-containing material, over the wheat grain. The processes after the tempering and grinding processes are executed in the same manner as in general wheat processing processes.
For the modification of wheat flour, TG is added at an amount of about 0.01 to 200 units per gram of the protein in wheat. The addition of TG below 0.01 unit gives poor effect on the improvement of the gelation potency; above 200 units, the enzyme reaction proceeds too excessively, so that when bread for example is prepared at such amount of TG, the resulting bread is hardened too much because of the suppression of the expansion, with the resultant improper appearance or texture. Preferably, oxidoreductase is added at an amount of about 0.01 to 200 units per g of the protein in wheat. Below 0.01 unit, the effect of the oxidoreductase over the modification of the color and flavor of wheat flour can hardly be exerted; an amount above 200 units is not preferable, from the standpoint of flavor. At least one of a substrate of the oxidoreductase, a protein partial hydrolysate, milk protein and a thiol group-containing material is added at an amount of about 0.0001 to 0.9 g per gram of the protein in wheat. Below 0.0001 g, noodles prepared by using the resulting wheat flour cannot get improved resilience or springiness; above 0.9 g, noodles prepared by using the resulting wheat flour are fragile with no viscosity, with the resultant inappropriate texture. For the modification of wheat flour, furthermore, the food excipients may satisfactorily be blended to the wheat flour.
When TG and the oxidoreductase are not used in an enzyme preparation form with at least one of a substrate of the oxidoreductase, a protein partial hydrolysate, milk protein and a thiol group-containing material, in accordance with the method of the present invention using the two types of the enzymes, these components may be used nearly simultaneously in the same way as the above-mentioned enzyme preparation is used, or independently, to exert their individual actions. If necessary, the individual components may independently be used in a divided manner at various stages or some multiple components can be used in a repetitive manner or can be used alternatively. Any of these methods using these components are within the scope of the invention. The description above for using the enzymes and the is remaining other components is also applicable to the treatment of fish paste and other food materials, other than wheat protein, as described below.
Wheat flour is divided in the following types: hardwheat flour, semi hard-wheat flour, medium hard-wheat flour, soft-wheat flour and durum semolina flour, and all of these wheat flours may be modified according to the present invention.
The resulting wheat flour modified through the action of TG and the oxidoreductase at the milling process is superior from various standpoints, as compared to the wheat flour modified after milling (JP-A-2-28603 1) and the wheat flour according to U.S. Pat. No. 5,279,839 (see JP-A-10-56948).
Processed food products prepared by using as a food material the modified wheat flour recovered in accordance with the invention may be prepared as described below.
According to conventional methods for producing wheat flour-processed food products, except for using the modified wheat flour of the present invention as the wheat flour, wheat-processed food materials can be prepared from a raw material the enzyme treated wheat flour recovered in accordance with the invention.
For the preparation of a loaf of bread, for example, the modified wheat flour recovered in accordance with the invention is mixed with yeast, yeast food and water by means of a mixer. Subsequently, the resulting dough is retained at 20 to 40xc2x0 C. for about 20 minutes to 10 hours, for a first fermentation to prepare a sponge dough. Secondary raw materials including water, salt, sugars, oil, and skim milk are added to and kneaded with the sponge dough to prepare bread dough. If necessary, the dough is left to rest for several hours for fermentation, and then, the resulting dough is divided in portions of suitable quantities, which are then left to rest for fermentation at 20 to 40xc2x0 C. for a given period of time, for the purpose of the formation of a network structure of wheat gluten. After the fermentation, the portions are charged in baking molds, for proofing. Satisfactorily, the proofing period is a term of approximately 40 minutes to 12 hours in total. After the termination of fermentation, the dough is baked in an oven at 180 to 250xc2x0 C. Even after long-term storage, the loaf of baked bread can retain excellent texture, compared with loaves of bread from general wheat flour types.
According to conventional methods except for the substitution of conventional wheat flour with the modified wheat flour of the present invention, pastas such as spaghetti and macaroni and noodles such as Japanese noodles (udon and soba) and Chinese noodles (including the sheets of gyoza and wang-tong), can be prepared. For the preparation of Chinese noodles, for example, the modified wheat flour and an aqueous solution of alkaline salts (kansul) are kneaded together to prepare dough; the dough is then left to stand at a preset temperature (aging process), followed by sheeting, combining and rolling; and the resulting dough is finally cut into pieces of a desired length and a desired width to be thus prepared as fresh Chinese noodle. The boiled Chinese noodle recovered by boiling the fresh noodle are with preferable hardness, good bite, and preferable elasticity; in other words, the resulting boiled Chinese noodle is resilient with resistance to the teeth, additionally with excellent noodle color and appearance.
Hereinafter, the method for modifying fish paste and the method for producing fish-paste processed products is described.
The treatment method with TG and oxidoreductase is exemplified by a method by means of the enzyme preparation of the present invention containing TG and oxidoreductase as the essential structural components thereof.
A process of adding the enzyme preparation comprises, for example, adding the enzyme preparation to fish after a leaching process for producing a fish paste. The other process comprises adding the enzyme preparation of the present invention to frozen fish meat as a raw material for producing a fish-paste product. By any of these methods, the gelation potency and color of general fish pastes can be modified and improved.
Herein, TG and the oxidoreductase are used at amounts of about 0.01 to 200 units and about 0.01 to 200 units, respectively, per gram of the protein in the fish paste to be used.
For producing a fish paste by the addition of the enzyme preparation, raw fish materials including sea-water fish such as Alaska pollack and nibe croaker (guchi; of the Family Sciaenidae) and fresh-water fish such as carp and sogyo (of the family carp), are used and subjected to meat recovery, leaching and dewatering processes, to recover dewatered fish. To the dewatered fish are added protein denaturing-preventive agents such as phosphate salts, and sugars and the enzyme preparation of the present invention according to the treatment method with TG and oxidoreductase. Then, a fish paste can be prepared.
During the process of producing fish-paste products, the enzyme preparation of the present invention is added to raw material fish pastes prepared from those sea-water fish and fresh-water fish, according to the treatment method with TG and oxidoreductase; and then, the resulting mixtures are subjected to cutting, setting, molding, heating and cooling processes, to prepare fish-paste products.
The resulting products are crisp to the teeth, and have elasticity and smoothness. From raw materials of sea-water fish pastes and fresh-water fish pastes prepared after landing, are prepared fish-paste products with such texture and additionally with modified color.
Pickles generally comprising components of 2.5 to 4.5% of salt, 1 to 3% of sugar, 0.5 to 1.2% of polyphosphate salts, 0.04 to 0.05% of nitrite salts, 0.08 to 0.25% of sodium absorbate and 5 to 15% of extraneous proteins (as a combination of plural proteins), in the form of a pickle solution, may be used for processing poultry and cattle meats. The components excluding the extraneous proteins do not differ so much, depending on the manufacturer, but each manufacturer has an absolutely unique technique how to make a combination of extraneous proteins. The combination of the extraneous proteins is of significance because the combination determines the quality of the resulting final products. Generally, the concentration of soybean protein and egg white as the extraneous proteins is about 2.5 to 6% in a pickle solution; and the concentration of caseins and whey protein is about 1 to 5% therein. When added to the pickle, TG disadvantageously causes the increase of viscosity; even when TG is contained in the enzyme preparation of the present invention according to the treatment method with TG and oxidoreductase, however, no increase of viscosity can be observed, under no influence of the combination of extraneous proteins or the concentration thereof. Thus, the final products such as ham, roasted pork and bacon prepared by injecting the pickle containing the enzyme preparation of the present invention into fresh meat are excellent in terms of smooth texture during swallowing and color.
In this case, TG and the oxidoreductase are used at amounts of about 1 to 1,000 units, preferably about 5 to 500 units and about 1 to 1, 000 units, preferably about 5 to 500 units, respectively, per 100 g of solid in the pickle.
At least one of a substrate of the oxidoreductase, a protein partial hydrolysate, milk protein and a thiol group-containing material may be used at about 0.01 to 50 g, preferably about 0.05 to 30 g per of solid in the pickle.
According to well-known methods, the enzyme-containing pickle of the present invention may be used for treating poultry and cattle meats at an appropriately selected amount, depending on the amounts of the enzymes required for the treatment of the amount of a protein to be treated.
The modification method of soybean protein according to the present invention is described below.
For example, water is added to defatted soybean, to extract the protein and remove the debris (okara); then, the resulting protein extract solution is recovered. The extract solution adjusted to pH 4.5 is subjected to isoelectric precipitation, followed by whey discarding to recover protein curd. Water is added to the curd, followed by neutralization, to recover a protein slurry. To the protein slurry is added the enzyme preparation of the present invention for enzymatic reaction, according to the treatment method with TG and oxidoreductase; subsequently, the resulting mixture is sterilized under heating and dried, whereby a soybean protein powder can be recovered. Soybean-processed products prepared by using the soybean protein, such as soybean curd, were excellent in view of texture, flavor and color.
Then, TG and oxidoreductase are used at amounts of about 0.01 to 200 units and about 0.01 to 200 units, respectively, per gram of the protein to be used.
The method for binding together foods, particularly poultry and cattle meats and cut fish pieces, is now described. According to the treatment method with TG and oxidoreductase, more specifically, bound food products with neat bound area could be recovered by dissolving the enzyme preparation of the present invention in water, coating the resulting solution on the binding area of a fresh steak meat piece or a cut fish piece thinly, shaping the resulting piece and subsequently retaining the piece at ambient temperature or a low temperature.
TG and oxidoreductase are used in this case at amounts of about 0.01 to 200 units and about 0.01 to 200 units, respectively, per gram of the protein to be used.
In accordance with the invention, the modification of raw food materials such as wheat flour, fish paste, poultry and cattle meats and soybean protein, as well as the industrial-scale production of processed food products such as wheat processed products, fish processed products and processed products from poultry and cattle meats, can be carried out with no specific difficulty, according to general production methods, except for the addition of the enzyme preparation of the present invention. No novel procedure or process is additionally required for general production methods.
The applicable range of the combination of TG and oxidoreductase in accordance with the invention is not limited only to the modification of raw food materials and processed food products. The processing with the combination of the two enzymes, for example the enzyme preparation of the present invention, is effectively applicable to targeted protein containing materials. The target materials include for example milk processed products such as ice cream and yogurt, sweets such as pudding, egg curd (in a shape of soybean curd prepared a from egg), jelly and mousse.
Having generally described the invention, a further understanding can be obtained by reference to specific examples which are provided herein for the purposes of illustration only and are not intended to be limiting unless otherwise specified.